The present invention relates to a perfected electromagnetic fuel injector for Diesel engine application, particularly of the type described in Patent Application n.67134-A/89 filed by the present Applicant on Feb. 28, 1989 and entitled "Diesel engine electromagnetic fuel injector".
Said injector comprises a plunger sliding inside the injector body, for controlling fuel passage between an injection chamber, supplied with fuel under pressure, and at least one injection orifice formed in an injection nozzle secured to the body; and an electromagnetic fuel metering valve for controlling fuel passage through a drain orifice between a control chamber, supplied with fuel under pressure, and a low-pressure chamber, and reducing the pressure of the fuel in said chamber by draining the same through said orifice.
Appropriate surface portions of the plunger are exposed to the fuel inside the injection and control chambers, so that the pressures inside the same and exerted on said surface portions raise the plunger when the pressure inside the control chamber falls to a given value, thus enabling fuel supply through the injection orifices on the nozzle.
Fuel under pressure is supplied to the injection and control chambers by means of a single fitting connected to a supply pipe and coming out inside a supply orifice formed in the body and communicating with the control chamber and with a supply duct for feeding fuel into the injection chamber; which duct is substantially formed inside a series of sleeves housed inside an axial hole in the body and inside which the plunger slides axially. Though highly satisfactory in term of operation and reliability, the above injector cannot normally be employed on all types of engines, by virtue of the fall in pressure depending on the size of the fuel supply orifice to the control chamber, and being specifically related to the design of the engine in question.